1. Field of the Invention
The present invention relates generally to a solar powered device and, more specifically, to a system and a method of power management for a solar powered device having an integral power management system.
2. Description of the Related Art
The use of solar energy as a source of energy for various types of devices is well known in the art. The solar energy is collected during the daytime via a solar panel electrically connected to the energy storage device. The energy stored in the energy storage device is discharged to power the device. For example, a solar powered light utilizes solar energy as a power source to illuminate the light, and the available energy is stored in an energy storage device, such as a rechargeable battery, or a storage capacitor.
Solar power is advantageously utilized in situations where other sources of power are not readily available. With respect to solar powered lights, examples includes outdoor landscape lights, or lights in buildings without electrical power, i.e. shed or portable restroom. While these and other types of solar powered devices work well under a variety of operating conditions, they periodically require service to replace the energy storage device, i.e. battery. A characteristic of an energy storage device, such as a battery, is a finite number of charge cycles. Therefore, the energy storage device has to be periodically replaced, and a long life cycle is more cost effective. At the same time, it may be difficult to service the solar powered device due to the physical location of the device. Thus, there is a need in the art for a solar powered device with an integral power management system that efficiently distributes energy to prolong the life of the energy storage device.
Accordingly, the present invention is a solar powered device and a method of power management for the solar powered device. The solar powered device includes a means for collecting solar energy, and a means for storing the collected solar energy having a plurality of energy storage devices, operatively connected to the solar energy collecting means via an energy transfer bus. The device also includes a control means for selecting to charge at least one energy storage device and selecting to discharge at least one energy storage device, such that the selected at least one discharging energy storage device is discharged to a predetermined level before selecting to recharge the selected at least one discharging energy storage device. The device still also includes a sensing means for sensing a predetermined condition for charging at least one energy storage device that is in electrical communication with the control means and an energy charge switching means responsive to a signal from the control means for selectively charging at least one of the energy storage devices to the predetermined charge level by transferring energy from the solar energy collecting means to the selected at least one charging energy storage device upon the occurrence of the predetermined charging condition. The device further includes a sensing means in electrical communication with the control means for sensing a predetermined condition for discharging the selected at least one energy storage device, and an energy discharge switching means responsive to a signal from the control means for selectively discharging energy from the selected at least one discharging energy storage device to the predetermined discharge level upon the occurrence of the predetermined charging condition. The device still further includes a load switching means responsive to a signal from the control means for delivering energy from the selected at least one discharging energy storage device to the load for operatively powering the solar powered device.
The method of power management for the solar powered device includes the steps of determining if a predetermined condition is met for supplying energy to the load, selectively discharging energy from at least one discharging energy storage device to the load, if the selected at least one energy storage device contains a predetermined level of stored energy for supplying energy to the solar powered device and checking the predetermined level of stored energy of another selected energy storage device, if the selected at least one energy storage device does not contain a predetermined level of stored energy, until selecting at least one energy storage device having a predetermined level of stored energy. The method also includes the steps of determining if a predetermined condition is met for selectively charging at least one energy storage device by transferring energy collected by the solar collector to the selected at least one energy storage device if the predetermined charging condition is met. The method further includes the steps of discharging the selected at least one discharging energy storage device to a predetermined discharge level before selecting to charge the selected at least one discharging energy storage device to a predetermined charge level.
One advantage of the present invention is that a solar powered device, which in this example is a light, is provided with an integral power management system for efficiently managing energy storage and consumption. Another advantage of the present invention is that a solar powered device is provided with an integral power management system that controls the charging and discharging of the energy storage devices according to their charge level, to extend the life of the energy storage devices. Still another advantage of the present invention is that a solar powered device is provided with reduced service needs. A further advantage of the present invention is that a solar powered device is provided that utilizes a storage capacitor to store solar energy. Still a further advantage of the present invention is that a method of power management for a solar powered device is provided that improves the life of the energy storage device by ensuring that the available energy stored in at least one of the energy storage devices is depleted to a predetermined level before recharging that particular device.